I would go for Yuasa battery every time, they certainly make best motorbike batteries.
Halfords HB 154 will fit, with any battery make sure positive and negative posts are in the correct place, and the correct size (small Japanese or large European terminals).
information below is taken from a manufacturers website
How to Care for your Battery - Maintaining your Warranty
1. Never leave your battery in a discharged state
When a battery has been fully charged it can quite happily be stored away for 2-3 months. However when a battery is flat, storing it for this period would almost certainly damage it beyond repair.
The reason behind this is a chemical process called sulphation. When a battery is charged this chemical process cannot take place. However, when the battery's voltage falls below 12.4V this process begins. The process causes sulphur crystals to form on the lead plates inside the battery, which in turn increases the battery's electrical resistance. The longer this process is allowed to continue the worse the effect. Eventually the battery will become so electrically resistant, that you will be unable to charge the battery, let alone draw power from it.
If this process is caught early you may be able to salvage the battery using a battery charger with a pulse charge function. This will partially break down the sulphur crystals but the battery will never reach its full capacity again.
Remember that if your battery fails due to sulphation it will not be covered under warranty. This kind of failure is classed as damage caused by the user through neglect.
2. Never overcharge your battery
Although you must always keep your battery as charged as possible when not in use, you must never overcharge it. Overcharging will cause the battery to heat up and its electrolyte will start to evaporate. In turn this will cause the battery's plates to break down, severely reducing the battery's ability to yield power.
Overcharging can be caused by a faulty regulator on a vehicle's charging system or by a manual charger being left on continuously at a high charging rate.
Fortunately, most chargers these days are now automatic and will turn themselves off once the battery has reached the end of a charging cycle.
This type of damage is also not covered under warranty, as the battery is clearly not at fault.
3. Avoid deep discharging when possible
Everybody knows that all batteries will deteriorate over time, and will eventually have to be replaced. Every time you use your battery then recharge it, its performance is ever so slightly decreased. This cannot be avoided. However, the severity of this decrement can be limited.
The way to achieve this is to not discharge your battery too deeply. Deep discharging causes the performance decrement to be more severe.
